In North America, of the people who buy cell phones, the percentage of

[[color=#0000ff]quote="brt"]I am a little bit confused.
If the sales of these phones as decreased in the past year and the no. of people buying these phones has increased which implies that the people are buying other phones instead of phones from local manufacturers. So how can this weaken the argument.[/quote]
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The percentage has decreased but, the overall number has increased, hence weakening the conclusion

This question is somewhat loosely constructed as A could be right in weakening if it included the percentage of people buying cell phones from local manufactureres.

''Other sources'' can't be trusted for good questions everytime.

Can someone please explain why A is the answer here?
My logic states that if A is to be evaluated, it would mean that the people buying cell phones have increased yet the people % purchasing from local shops have decreased. i.e. if 100 people were buying cell phones, 55 people bought from local stores ( a random 55% assumption). Now this year, the # of people buying cell phone is lets say 120, but we see that there is a reduction of 5% so that means , people still buying from local stores becomes 50% now, this means that the number of people buying cell phones from the local store is 50% of 120 = 60, thus there is an increase in the number of people buying the cell phone and hence it is not affective them negatively.

let us assume another example where the number of customer increased by 5 people i.e. 105 people this year will buy cell phone, 50% of this is 53 which is less than 55 ( what we assumed initially) since considerably can mean any number, how do we justify what considerably is ?